SPOILER AHEADJust walk back the way you came from. However... if you already gone to far, your only choise might be to join the clouds and go even farther. Some guys say that's how you "win the game". I wouldn't call it that way. However it seems to be indeed a way to end the game... it might be that this is meant to make the game kind of a metaphor... for me it was at least a nice surprise.